Elisabeth Moss as Peggy Olson and Jon Hamm as Don Draper in a scene from "Mad Men" Season 7. / AMC

by Patrick Ryan, USA TODAY

by Patrick Ryan, USA TODAY

Warning: Contains major spoilers about the midseason finale of Mad Men Season 7.

Well, that was an uncharacteristically happy finish.

Mad Men, the highbrow drama known for its eternally gloomy characters, wrapped the first half of its seventh season Sunday night with a gleeful song-and-dance number. More precisely, a now-deceased Bert Cooper - flanked by beautiful, young secretaries - delivered his rendition of The Best Things in Life Are Free (recorded by Jack Hylton in 1928) to Don Draper in a hallucination at the end of the episode, titled "Waterloo."

Luckily for fans of the series - who still have to wait another year for the last batch of episodes of the final season - there are no major cliffhangers or unresolved issues to mull over in the months to come. Nevertheless, here are some of the biggest defining moments of Season 7 (so far):

R.I.P. Bert Cooper. Sterling Cooper & Partners' oldest founder died toward the end of the episode (saying one final "bravo" as he watched the moon landing on TV). His sudden passing left the fate of agency - which was ready to oust Don at the beginning of the hour - up in the air. That is, until Roger struck a deal with McCann-Erickson, which agreed to buy out the firm, making SC&P a subsidiary and all the partners very rich. More importantly, after six episodes of struggling to get his life back on track, Don has finally re-entered the office hierarchy - a bittersweet victory for the ad-man antihero, who now has no one to share his success with.

R.I.P. Don and Megan's marriage. This relationship has been on the rocks for a long time - Megan even corralled her actress friend into a threesome to try to renew the "spark" - but it still may have surprised viewers to see Don and Megan end things so amicably over the phone: Megan, in California, and Don, contemplating a move to the West Coast when he believes he's been fired. "You don't owe me anything," Megan says to Don, who assures her that he will continue taking care of her. Oh, Disneyland and Zou Bisou Bisou ... what distant memories.

"Family supper at Burger Chef." Of all the characters, Peggy has had one of the most eventful arcs of Season 7: Michael Ginsberg gifted her his severed nipple in a box after confessing his manic love. After much headbutting (and drinking), Don began working under her. She later reconciled with Don in a late-night, whiskey-infused slow dance to Frank Sinatra's My Way in "The Strategy." Her biggest moment was in the midseason finale, when she stepped up to the plate and delivered a heartfelt pitch for Burger Chef, (reminiscent of Don's Kodak Carousel spiel of Season 1) and ultimately won the account. She's come a long way since her Relax-a-Cizor days as a secretary.

Betty Draper 2.0. Early in the season, sulky teenage Sally ditches her boarding-school buds in search of her dad at SC&P, later confronting Don about how much pain his affair with Sylvia caused her. Don, in turn, confesses the true reason he's not at the office (his forced vacation), and the dust begins to settle between the strained father-daughter pair, culminating in Sally's dry admission of, "Happy Valentine's Day. I love you." In "Waterloo," Sally catches the eye of not one, but two boys, and masters the art of lighting her cigarettes - becoming more and more like her manipulative mother Betty each time she's onscreen.

"West Coast Pete" has a sunnier outlook. Viewers' feelings for Pete Campbell have run the gamut from loathing to sympathetic over the years, but in Season 7, it's been pretty difficult not to like the guy. Since moving to California to head the new SC&P office with Ted Chaough, he's gotten a new girlfriend, a more laid-back wardrobe, and an appetite for pastrami sandwiches (with coleslaw on the sandwich). But as Pete's trip back to New York proves - when his toddler-age daughter, Tammy, doesn't even recognize him, and soon-to-be-ex-wife Trudy assures they're getting a divorce - no one in the Mad Men universe can stay happy for long.

Bob is back. Just when fans had given up hope that he'd be returning, the ever-elusive Bob Benson returned in the midseason's penultimate episode, "The Strategy," with news that SC&P is losing the Chevy/XP account - and a job offer from Buick. So how does he decide to celebrate? By spending the day with Joan Holloway and clan, later proposing to Joan ... and getting flat-out denied. "You shouldn't be with a woman," Joan says, reaffirming Bob's sexuality, and adding that she would rather die hoping for real love than live financially stable in a sham marriage with Bob.

"I'm not stupid. I speak Italian."Speaking of strong ladies, Joan's not the only woman sticking up for herself: Betty Francis (field-trip picnics and Sally's nose aside) has really come into her own as a character in Season 7, refusing to be silenced by her politician husband, Henry, at a dinner party and asserting that she's tired of having her opinions dismissed. Perhaps the ex-Mrs. Draper will embrace the feminist movement if the story moves into the early '70s?